This invention relates to an apparatus for connecting a respiratory device with a patient having a breathing tube, such as an endotracheal tube or tracheostomy tube. The breathing tube is insertable into the patient's trachea and is connected to a source of breathing gas, such as air or oxygen. An inflatable cuff surrounds a portion of the breathing tube adjacent to the distal end of the breathing tube. When inflated, the cuff forms a seal with the inner walls of the patient's trachea, thereby preventing the breathing gas from escaping through the patient's mouth. Specifically, the inflatable cuff is connected to a connection line which provides an inflation gas, such as air or oxygen. When inflated, the cuff forms a generally air-tight seal with the patient's trachea so the breathing gas delivered from the breathing tube is forced to flow towards the patient's lungs rather than back up his/her trachea. It is desirable to control the air pressure within the cuff in order to maintain a seal between the cuff and the patient's trachea and in order to minimize or reduce the risk of over-inflating the cuff and causing trauma to the patient's trachea.
One currently-known apparatus for regulating the pressure in the cuff is disclosed in U.S. Pat. No. 3,794,043 (the '043 patent). The '043 patent discloses an apparatus used for the artificial respiration of patients. After the breathing tube has been inserted into the trachea of the patient, a syringe is connected to a valve for inflating the cuff to a pressure between 16 and 25 millimeters of Mercury. Simultaneously with the inflation of the cuff, a pressurized air reservoir connected to the valve is also filled. After removal of the syringe, the valve maintains a constant pressure in the cuff by pressure differentiation between the cuff and the air reservoir. This arrangement is such that the air from the pressurized air reservoir can flow back to the cuff comparatively easily while the air in the opposite direction, i.e. from the cuff to the pressurized air reservoir, should be with a reduced flow rate to prevent leaks from occurring between the cuff and the trachea.
Although this design performs in a satisfactory manner, it is relatively complex and expensive to produce, and it requires relatively sensitive materials. For example, the valve in this design includes two housings positioned within each other, where the inner housing receives a mushroom-shaped body serving as a valve member, with bottom end thereof forming the sealing surface of the check valve that controls entry of air into the valve. A separate push rod, which is made of plastic, is provided for actuating the check valve. During the filling of the cuff, by means of the syringe, the check valve has to be displaced to open the valve. This design includes a relatively high number of parts and is relatively complex, both of which may be disadvantageous.
Additionally, the mushroom-shaped body serving as the valve member is made of a natural rubber. Specifically, the rubber balloon is clamped and fixed at the valve body between the two housings positioned within each other and the head of the mushroom shaped valve body is positioned within the balloon of natural rubber in combination with its margin engaging the top side of the valve and relief openings within the head the part is acting as a control valve. It is undesirable to use natural rubber because it may be subject to premature wear.
It is therefore desirable to provide an apparatus for connecting a respiratory device with a patient having reduced part complexity and reduced manufacturing costs, as well as improved durability and potentially reduced part wear.